The present invention relates to design of inlet valve ports, valve shrouding and the combustion chamber of a cylinder head of an internal combustion engine and, more particularly, to an apparatus and a method for analyzing particular designs of the inlet valve shrouding of particular cylinder heads.
In designing cylinder heads for combustion chambers of internal combustion engines, it is desirable to know the type of fluid flow pattern present within the cylinder while the cylinder valves are open and the cylinder is being filled with a fluid stream of air and fuel. The type of fluid flow pattern aids the designer in determining optimum characteristics for that particular combustion chamber and cylinder head. Also, the optimum fluid flow pattern aids the engine in producing more power and in reducing emissions.
Generally, two types of fluid flow patterns exist in combustion chambers of automotive internal combustion engines. One type is what is known as a swirl pattern. The fluid flow in a swirl pattern travels along the combustion chamber wall in an arcuate path substantially about the axis of the cylinder bore. The fluid flow moves in a helical pattern, as seen in FIG. 5.
The second type of fluid flow pattern is what is known as tumble flow. Tumble flow follows a substantially arcuate path substantially transverse to the axis of the cylinder bore, as shown in FIGS. 2-4.
Tumble flow is believed to offer significant advantages over other types of flow in that it promotes mixing of fuel and air within the combustion chambers which reduces the ignition delay period or in other words increases the burn rate of the engine's air/fuel. As a result, tumble flow promotes combustion stability within the combustion chambers for combustion. Additionally, tumble flow provides for better emission characteristics and results in improved engine operating economy. Thus, it is desirable to have combustion chambers which exhibit tumble flow characteristics.
With the advantages provided by tumble flow, the question arises as to why all combustion chambers do not have tumble flow. It is believed that apparatus does not exist which enable viewing of the flow patterns within a combustion cylinder to enable determination of the flow patterns within the combustion cylinder.
Therefore, it is desirous to have an apparatus which enables a determination of whether or not tumble flow will exist in a combustion chamber for a particular cylinder head. Also, the apparatus should provide information useful in the design of the cylinder heads which produce tumble flow. The apparatus should enable evaluation of tumble flow in the combustion cylinder in an attempt to optimize the flow pattern. Accordingly, it is an object of the present invention to provide the art with such an apparatus.
The present invention provides the art with an apparatus which enables viewing of flow patterns within a simulated combustion chamber. The present invention provides information useful in designing inlet valve ports of cylinder heads which produce tumble flow in their respective combustion cylinders. The present invention enables adjustment of a simulated piston to simulate various positions of a piston during the stroke of the piston in the simulated combustion chamber to enable analysis of the flow patterns within the combustion chamber cylinder. The simulated piston in the subject apparatus is in the form of a porus screen so that a continuous flow of air can pass from the valved inlet port of the cylinder head into the combustion chamber. The apparatus also uses visible and trackable lightweight members in the combustion chamber which move with the air flow away from the valved inlet ports toward the simulated piston or screen. When the lightweight members engage the piston simulator, they move along its surface in a manner similar to the flow pattern of air in an engine with a non-porus piston. Movement of the lightweight members away from the simulated piston and toward the valved inlet port simulates the air flow in an engine with a non-porus piston even though the general direction of air flow in the subject apparatus is from the ports to and through the simulated piston.
From the following detailed description taken in conjunction with the accompanying drawings and claims, other objects and advantages of the present invention will become apparent to those skilled in the art.